In the present era, location based services (LBS) are increasingly deployed in wireless networks that can be accessed by numerous types of wireless devices, including mobile telephones, smart phones, tablet computers, hybrid communication devices, and other devices. The range of LBSs includes services to identify a location of a person or object, including simply providing a location to the user. Examples of LBS include location-based information such as providing the nearest banking automatic teller machine (ATM) or the whereabouts of a friend or employee; parcel tracking; providing advertising directed at potential customers based on the current customer location; personalized weather services; and location-based games. LBSs are typically provided via a wireless network to which a user of a wireless device may subscribe or connect to as a casual user. Once connected, the current user location may be derived from various types of information.
Common techniques used to determine a wireless device location include global positioning satellites (GPS) locationing and uplink time difference of arrival (u-TDOA or, simply, TDOA). In systems that employ GPS-based locationing, a communications chip within a wireless device receives signals from multiple satellites and uses the received signals to determine location of the wireless device. In TDOA, multiple cell towers, or base stations, receive a signal output by a wireless device. The difference in arrival time of the output signal at the different towers is used to calculate the location of the wireless device. Other techniques include the received signal strength (RSS), which may be measured by either a mobile device or the receiving sensor at a fixed base station. Knowledge of such factors as transmitter output power, cable losses, and antenna gains, as well as the appropriate path loss model, facilitates solving equations for the distance between a wireless device and base station. Variations of RSS include WiFi based RSS and wireless wide area network (WWAN)-based RSS.
Although many different technologies are thus useful for supporting LBS type services, the full benefit of harnessing information from multi-radio terminals for LBS has not yet been realized. Moreover, many wireless terminals may lack certain devices, such as a GPS device, which may render the accuracy of locating the wireless terminal less than optimal.
It is with respect to these and other considerations that the present improvements have been needed.